# Help!! step by step answer to solving this inequality!! (Further maths as)

Answers

Are you sure you have typed the question correctly the answers do not come out particularly nice. Also is that 3/4 x or 3/(4x)?

04 October 2013

Firstly I'm going to assume you mean (5x+3)/(4x-7) ≥ 2.Doing inequalities is pretty much the same as any other algebra - what you do to one side do to the other. In this case the first thing to do is get rid of the pesky denominator. So multiply both sides by (4x-7):5x + 3 ≥ 2(4x-7)Multiply it out just like normal:5x + 3 ≥ 8x -14Gather like terms. We want something in the form ......≥ x so we need all the xs on one side and all the numbers on the other. The easiest thing to do is take 5x from each side, which leaves us with: 3 ≥ 3x -14Now add 14 to each side:17≥ 3xWe don't want 3x we just want one x so divide through by 3:17/3 ≥ xAs a matter of form we usually write inequalities with the x on the left hand side so we need to swap this around. If 17/3 is greater or equal to x that means x is less than or equal to 17/3. So swap sides and reverse the sign. x ≤ 17/3Job done.

04 October 2013

The question is: (5x+3)/(4x-7) is greater than or equal to zero.And also, you have to multiply by the square of the denominator- not just cancel out the denominator- that's all I know but I can't go on from there...Please, please help!!

04 October 2013

Sorry I meant greater than or equal to 2

04 October 2013

solution.pdf

04 October 2013

@Liz Herbert multiplying both sides of an inequality is generally not a great idea since it can introduce sign errors. And it appears you have made one. @lala12345 Multiplying by the denominator squared is a good idea since a square number is always greater than zero and hence there will not be any sign errors.Please see attached doc to see how I would approach this problem. I apologise for any mistakes I had to do it in a rush.

04 October 2013

@lala12345 once you have multiplied by the denominator squared you would multiply out the brackets and have a relatively simply quadratic inequality.

04 October 2013

Thanks jack,I understand how to do it now :)

08 October 2013

daum_equation_1392308939691_th_3.png

13 February 2014

image.jpg

30 October 2014

Hello,lala12345,I shouldnt have disturbed you but the answers posted below are somewhat wrong.When we are faced with inequality, we cannot deal it the same way as we deal with equality.Since 4x-7 can also be negative, so we cant simply multiply it to other side because if we multiply the inequality with negative one, it changes the inequality sign.rather than multiplying 4x-7 we multiply by (4x-7)^2 to both sides and solveSo(5x+3)(4x-7)>= 2(4x-7)^220X^2-35x+12x-21>= 32x^2 -112x +9812x^2-89x+119<= 0 so answer is 7/4<=x<=17/3

01 November 2014

The denominator may be a negative value and therefore may reverse the inequality. Therefore instead of multiplying through the the denominator you need to multiply by (4x-7) squared.This should leave you with:(5x+3)(4x-7)>= 2(4x-7)^220x^2-23x-21>=2(16x^2-56x+49)0>=12x^2 -89x+119If you then use the formula or complete the square to solve and find the roots of the equation, you should get 7/4 and 17/3.By drawing a quick sketch of this quadratic, it has a positive value of x squared.and two positive roots so please see the sketch on the whiteboard.So the solution is7/4<=x<=17/3

02 November 2014

sketch-4.svg

02 November 2014

it is 52

02 November 2014

Hi there,Solving an inequality is almost exactly the same as solving an equality, apart from one crucial thing, if you multiply or divide both sides by a negative number you need to reverse the inequality.So for your question you want to: group all the numbers on the right by adding 7 to both sides.this leaves the xs on the left, you then want to simplify the xs by bringing them together with the same coefficient, which would be (5 + 3/4) which you can work out. It will leave you with some fraction in front of the x, you then want to get the x on its own by multiplying both sides of the inequality by what is on the bottom of the fraction and divide both sides by what is on the top of the fraction.Non of these things should change the direction of the inequality since you haven't multiplied or divided by a negative number and your inequality should be solved for x.Hope this helped, get back to me if you have any questions.

07 September 2015

I just realised that I misread your question, I thought that 3/4 was a coefficient of the second x, and that you already have a very suitable description of the solution, please refer to Wendy D who has solved your problem

07 September 2015

profit3.docx

28 December 2015

Your answer is x >= 36/23.All you have to do is simplify both sides of the equation, then isolate the variable.

21 March 2016

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